1- Field of the Invention
This invention relates to a method for enhancing and accelerating the repair of chronic cellular and molecular damage to the skin.
2- Description of the Prior Art
Recently it has become apparent that chronic free radical damage to the skin either from UV irradiation or from environmental pollutants causes specific deterioration of the epidermis and dermis that is distinct from the acute effects of UV irradiation and is not simply an acceleration of the inevitable age-dependent alterations denoted in the dermatologic literature as "intrinsic" aging.
The particular chronic cumulative damage caused by UV irradiation is denoted in the medical dermatologic literature as "photoaging" and is manifested clinically by wrinkles, dry, waxy skin, and a variety of benign and premalignant as well as malignant neoplasms. All of these clinical changes are the result of specific salient histologic features of actinically damaged skin which have been characterized and are (i) hypertrophy of the epidermis with cellular atypia and thickening of the stratum corneum, (ii) solar elastosis with tangled, degraded dermal elastic tissue degeneration into an amorphous mass (Kligman AM, JAMA, 210, 2377, 1969), (iii) degradation of dermal collagen to become larger rope-like structures (Bentley JP, J. Invest. Dermatol. 73, 80, 1979), and (iv) hypercellularity of the dermis (Andrew W, et al: Gerontologica 10, 1, 1964).
Topical application of retinoic acid (Retin A, Ortho Pharmaceutical Corporation) reportedly results in epidermal repair with thinning of the excessive stratum corneum and normalization of the cellular atypia of the deeper layers of the epidermis as well as the formation of new, fine fibrillar dermal collagen and restructuring of the damaged dermal elastic tissue to the normal non-tangled, fibrillar form. (Kligman AM, Leyden JJ, Kligman LH, Grove GL, Topical Retinoic Acid for the reversal of Photoaging, Communication from Ortho Pharmaceutical Corporation, February 1986; Weiss JS. Ellis CN, Headington JT, Tincoff T, Hamilton TA, Voorhees JJ, JAMA 259, 527, 1988). However, the use of topical retinoic acid usually causes discomfort, flaking and erythema at the beginning of treatment and increased sensitivity to sunlight (Burke KE, Graham GF, North Carolina, New York, JAMA 260, 3130, 1988).
It has previously been shown that topical application of selenoamino acids leads to transdermal absorption with enhanced levels of selenium in the skin to provide protection from UV irradiation induced skin damage, significantly reducing the incidence of skin cancers following UV light exposure (U.S. Pat. No. 4,865,840 Sep. 12, 1989). The levels of selenium that were effective gave no evidence of any topical or systemic toxicity.
A need exists for additional methods for enhancing and accelerating the repair of chronic cellular and molecular damage to skin, especially methods not having the side effects of topically applied Vitamin A.